CiQUS researchers demonstrate that chemical methods can compete to develop nanometer-thick YIG films with the quality required for spintronic devices and other high-frequency applications.
Cubic Yttrium Iron Garnet (YIG) is a technologically important material due to its excellent magneto-optical properties, high electrical resistivity, and a very narrow ferromagnetic resonance, which makes it particularly suitable for applications in filters and resonators at microwave frequencies. These properties depend on the precise stoichiometry and distribution of Fe3+ ions among the octahedral/tetrahedral sites of a complex structure, which required the use of high-vacuum deposition methods for the fabrication of high-quality YIG thin films. Therefore, the development of simpler, cheaper, and more versatile techniques to chemically synthesize high-quality epitaxial YIG thin films has become a scientific and technological challenge of considerable relevance in the field.
CiQUS researchers have reported in Physical Review Materials (Editors' Suggestion) the chemical solution (water-based) deposition of high-quality epitaxial crystalline YIG thin films (∼15nm thick) on (111) Gd3Ga5O12 (GGG), with very high structural, chemical, and magnetic homogeneity. These high-quality YIG thin films show magnetic properties comparable to those obtained using physical methods, and FMR, which demonstrates the good magnetic homogeneity of the films.
These results demonstrate that chemical methods can compete to develop nanometer-thick YIG films with the quality required for spintronic devices and other high-frequency applications.
Professor Rivadulla has already published a number of papers applying this technique to other high quality epitaxial thin-films, down to 4 nm thick, and bilayers, of different oxides and nitrides. They have also obtained an outstanding homogeneity even in large areas (proof of concept up to 1" substrate).
Thus, for example, they have already prepared manganites, cobaltites (perovskites) and their combinations; Yttrium Iron Garnet (YIG) over Gadolinium Gallium Garnet (GGG) and Yttrium Aluminium Garnet (YAG); Ferroelectric BiFeO3 on LSMO; ZnO over sapphire; Chemical deposition combined with MBE (e.g. multilevel device integrated on silicon).